C++ Transform Function: Usage Guide

In C++, the transform function is used to perform a specified operation on elements in a container and store the results in another container.

The basic syntax of the transform function is as follows:

transform(first1, last1, result, unary_op);

One of them is:

1. first1 and last1 represent the range of elements to be processed in the input container.
2. Result represents the target container for storing the results.
3. unary_op is a function object that performs an operation on each element in the input container.

For example, the following code demonstrates how to use the transform function to multiply each element in a vector by 2 and store the results in another vector:

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> vec1 = {1, 2, 3, 4, 5};
    std::vector<int> vec2(vec1.size());

    std::transform(vec1.begin(), vec1.end(), vec2.begin(), [](int n) {
        return n * 2;
    });

    for (int num : vec2) {
        std::cout << num << " ";
    }

    return 0;
}

The output is:

2 4 6 8 10

In the example above, we used a lambda expression as the unary_op to multiply each element in the input container by 2. The transform operation stored the results in vec2.